Identify what the habit is solving
Perhaps you need a snack on the journey home, or your workday makes food preparation awkward. In that case, a repeatable option can be useful. If you are buying a bar only because you feel every day needs a protein product, pause and look at your usual meals first.
Write down the moment you actually use it. A specific purpose makes it easier to judge whether the habit is helpful than a general idea that more protein must always be better.
Keep room for other foods
A regular favourite can sit alongside variety. You might choose a bar on office days, leftovers when you are at home, and fruit with another snack on a weekend. There is no need to make every day identical.
Watch for a pattern in which a small snack keeps replacing a meal you intended to have. The practical fix may be better meal planning rather than a different brand of bar.
Check fit, not just frequency
Read the ingredients and portion information for the bar you buy. If it contains something you need to avoid, eating it less often is not a substitute for choosing a suitable product. For medical dietary needs, use individual guidance.
Taste and comfort count too. If you dislike a snack or it does not agree with you, there is little reason to keep choosing it simply to maintain a routine.
Review the habit after a week
Notice how many bars you eat, what they replace and what they cost. Did they help you bring food from home, or become an extra purchase you did not particularly want? A small adjustment to your shopping list may solve either issue.
You do not need a universal daily rule. Choose food that is suitable, enjoyable and practical, and keep the wider pattern of your meals in view.